Front End Control Registers
136
SNIU028A – February 2016 – Revised April 2016
Copyright © 2016, Texas Instruments Incorporated
Front End
3.7.11 Pre-Bias Control Register 0 (PREBIASCTRL0)
Address 0x0008_0028 – Front End Control 2 Pre-Bias Control Register 0
Address 0x000B_0028 – Front End Control 1 Pre-Bias Control Register 0
Address 0x000E_0028 – Front End Control 0 Pre-Bias Control Register 0
Figure 3-19. Pre-Bias Control Register 0 (PREBIASCTRL0)
17
16
15
8
7
0
PRE_BIAS
_POL
PRE_BIAS_EN
PRE_BIAS_RANGE
PRE_BIAS_LIMIT
R/W-0
R/W-0
R/W-1111 1111
R/W-0000 0000
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 3-13. Pre-Bias Control Register 0 (PREBIASCTRL0) Register Field Descriptions
Bit
Field
Type
Reset
Description
17
PRE_BIAS_POL
R/W
0
Configures polarity of received error voltage
0 = Error equals Vref-Vin (Default)
1 = Error equals Vin-Vref
16
PRE_BIAS_EN
R/W
0
Enable Pre-Biasing of Error ADC (Ramp should be disabled during pre-biasing, bit 0
of Ramp Control Register)
0 = Pre-Biasing has not been initiated (Default)
1 = Pre-Biasing by hardware has been enabled
15-8
PRE_BIAS
_RANGE
R/W
1111
1111
Sets the acceptable range around the zero error point. If Error ADC value stays in
range for number of samples specified by PRE_BIAS_LIMIT (Bits 7:0),
PREBIAS_STATUS (Bit 0 of Ramp Status Register) is enabled. Range will be +/-
PRE_BIAS_RANGE around zero error point.
7-0
PRE_BIAS_LIMIT
R/W
0000
0000
Sets the acceptable number of samples in which the Error ADC value stays in range
before asserting PREBIAS_STATUS (Bit 0 of Ramp Status Register). Counter limit
ranges from 0 to 255. If PREBIAS_STATUS is set, it will take PRE_BIAS_LIMIT
samples outside of acceptable range before clearing PREBIAS_STATUS.